A typical prosthetic leg and foot includes a socket, pylon, and foot. A socket is commonly referred to as the portion of a prosthesis that fits around and envelopes a residual limb or stump, and to which prosthetic components, such as a foot, are attached. When providing a socket to an amputee, it is essential to properly fit the socket and align various parts of the prosthesis to the amputee. Fitting and alignment of the socket and the parts are difficult tasks to perform, and require extensive knowledge, training and skill for the prosthetist.
Typically, sockets for definitive prostheses are customized for a residual limb of a wearer. According to one method, the sockets are formed over a model of the stump, such as one formed by plaster-of-Paris, to be used to distribute forces between the socket and the stump in a comfortable way to the amputee. In another method, the socket may be obtained from computer aided design by modeling the shape of the stump, and subsequently forming a model. Once the model is obtained in either of these methods, a socket is formed over the model by using fabric and liquid plastic resin to obtain a definitive rigid socket customized to a limb.
Proper fitting of a socket to the stump is critical to the success of the prosthesis. The socket must fit closely to the stump to provide a firm connection and support, but must also be sufficiently loose to allow for circulation. In combination with proper fitting, the socket must transfer loads from the residual limb to the ground in a comfortable manner.
Most prosthetic sockets are permanently formed to a customized shape that is static, meaning the socket does not account for shape and volume fluctuations of the residual limb. When there are shape and volume fluctuations, the fitting of the socket is impeded, with these sockets causing discomfort, pain and soft tissue breakdown of the stump. Conventional sockets tend to be bulky and cumbersome to wear, and may be difficult to don making the residual limb uncomfortable when worn.
As to methods of attaching the socket to the residual limb, conventional sockets rely on different mechanisms such as negative pressure or a friction or tension based interface. Conventional sockets may have poor force distribution on the residual limb causing a concentration of pressure on a certain area of the stump. This poor distribution of pressure causes pain, discomfort, and tissue breakdown. Conventional sockets generally are not breathable which results in undesirable temperature and humidity within the socket.
For certain types of amputations such as disarticulation amputations where the limb is separated at a joint, it is difficult to create sockets which are not bulky and provide use of the natural anatomy. Conventional sockets for disarticulation amputations use a rigid socket which requires that the opening for the socket be larger than the joint to allow for donning and doffing. The rigid sockets generally have a general uniform shape which receives a large portion of the residual limb and the space between the residual limb and the interior of the rigid socket wall is filled in with a soft or cushioning material.
Besides the socket, a leg prosthesis includes a prosthetic foot and depending on the level of the amputation, a pylon between the socket and the foot. The length of the pylon must also be customized for the amputee's height and level of amputation. A prosthetist aligns the pylon, the socket, and the foot to minimize undesired forces produced during gait on the user and prosthesis and to provide the user with a more symmetric gait. The alignment of the prosthesis also affects the pressure distribution at the stump and socket interface.
It is desirable to provide a simplified and compact prosthesis system that overcomes the drawbacks over known prosthesis systems. Particularly, it is advantageous to provide a complete prosthetic limb system that is off-the-shelf and capable of accommodating a variety of residual limb sizes. It is also desired a socket system of the prosthetic limb system be adjustable to allow for volume and shape fluctuations, and in effect, provide a dynamic socket as opposed to the known static sockets. The adjustable socket can better adjust for pressure distribution, and maintain comfort to the amputee over a range of care and residual limb conditions. It is further desired that the pylon and the foot of the prosthesis be adjustable to accommodate a variety of users and gaits.
According to an embodiment, the adjustable socket system has a distal end portion having an axis, and a frame has a plurality of elongate fingers longitudinally extending from the distal end portion. Each elongate finger defines at least two segments pivotally connected to one another and extending in a longitudinal direction relative to the distal end portion. The at least two segments are pivotable inwardly or outwardly relative to the axis. At least one elongate element connects to the plurality of elongate fingers and forms part of a circumference of the adjustable socket system in combination with the fingers of the frame. The fingers may be formed from a flexible material such as resin reinforced with carbon fibers.
The distal end portion may define a plurality of base elements extending laterally and extending longitudinally in part to couple to a respective one of the segments of each of the plurality of fingers. The distal end part has a proximal contour adapted to receive a distal end of a residual limb, and sized to accommodate a large variety of differently shape residuums. The plurality of base elements may be rigidly secured to the respective one of the segments of each of the plurality of fingers.
A sleeve has a plurality of pockets wherein each of the pockets extends over a respective one of the plurality of fingers. The sleeve carries the at least one elongate element. The sleeve may be formed from an inelastic textile. The at least one elongate element includes a lace slidably connecting to each of the plurality of pocket, and the at least one elongate element may be a textile lace that is inelastic. Each of the pockets may be slidably removable from the respective one of the plurality of fingers.
According to a variation, the at least one tensioning device is connected to the frame and the at least one elongate element connects to the plurality of fingers to form at least part of the circumference of the socket system. The at least one tensioning device is mounted to the distal end portion below the frame. The at least two segments define a plurality of channels for directing the at least one elongate element along a surface of the at least two segments. The at least two segments define opposed apertures corresponding to opposed side walls and in communication with a respective one of the plurality of channels. The at least one elongate element extends through the opposed apertures.
According to another variation, the at least one elongate element has at least one end adjustably secured to the distal end portion. Adjustment of the at least one elongate element is arranged to change tension in the at least one element.
In another embodiment, an adjustable prosthetic socket system has first and second opposed sides, and includes a socket frame having a first component arranged along a first side of the socket system and a second component arranged along a second side of the socket system. The first component is connected to the second component. A tubular insert is arranged on the interior of the socket frame forming an interior surface of the socket system. At least one tensioning element connects the circumferential insert to at least one of the first component and the second component. At least one tensioner is attached to the at least one tensioning element that draws in and releases the tensioning element to adjust the circumference of at least one area of the socket system. A partial enclosure may laterally extend from each side of the first component.
The adjustable prosthetic socket system may also include a plurality of tensioning element guides arranged longitudinally between the first component and the second component. The at least one tensioner is attached to the second component and the at least one tensioning element connects the plurality of tensioning element guides to the second component. The plurality of tensioning element guides is connected to the tubular insert and the partial enclosure. The first component is an adjustable spine, the second component is a rigid spine, and the tubular insert is flexible.
Other embodiments are presented below in accordance with the description and various drawings.